1. Field of the Invention
This invention relates to a valve and, more particularly, to a fluid actuated shut-off valve having a valve stem connected to a reciprocal piston positioned in a housing which forms a sealed fluid chamber around the piston and is rotatably mounted on a base to permit selective positioning of the housing for connection to a source of pressurized fluid.
2. Description of the Prior Art
Shut-off valves that are provided with an actuator which is remotely controlled, such as a pneumatic or hydraulic actuator, are well known in the art. U.S. Pat. No. 4,201,366 discloses in a bellows valve a remotely operable air actuator connected to the upper end of a valve stem having a lower end sealed within a bellows. Supplying compressed air to the operator lifts the valve stem off the valve seat to open the valve. On loss of the actuating air pressure, the valve stem is automatically lowered by the biasing force of a compression coil spring to close the valve. Thus, the valve is normally maintained closed in the absence of air pressure to the air operator. Other remote controlled valves are disclosed in U.S. Pat. Nos. 3,789,875; 3,913,883; 3,958,592; 3,993,284; 4,274,432 and 4,306,583.
A frequently encountered problem with remotely operated pneumatic valves is a loss of fluid pressure in the chamber of the air operator. The air operator includes a piston which is reciprocally movable in a housing. The piston must be free to reciprocate, while at the same time, a fluid-tight seal must be maintained around the piston as it reciprocates to prevent loss of the fluid pressure for opening the valve and maintaining the valve in an open position. The air operator seals, therefore, must be operable to maintain a sliding seal. This requires the seal around the piston to be operable to sustain many cycles of reciprocation without wear and resistant leakage.
A further problem frequently encountered in remotely controlled pneumatic shut-off valves is the mounting and connection of the valve to a supply of pressurized air. In many applications, the valve is positioned where connection of the operator to an air supply is difficult to complete because of limited space around the valve and the relative position of the part of the air operator to which the supply line is connected.
Therefore, there is need in a remotely operable pneumatic shut-off valve to provide an air operator that is movable to a selective position to facilitate east of connection to the air supply line.